Car-retarder system



March 3, 1931- N. c. L BROWN GAR RETARDER SYSTEM Filed Feb. 14, 1927 HG. 3 g 6 24' 4 27 23 MUWM s 1 Patented Mar. 3,1931

; SIGNAL COMPANY.

NED o. L. BROWN, or soo'rTsvILLn iqrnvv 03K," assienon TO GENERAL RAILWAY r or ROCHESTER, NEW YORK s it oAR-aE'rARnEas s'rnM a plicatibirfiiea February 14,1927, Serial No. 1( i8,033.

'lhis invention relates in general to railway car brake apparatus, and has more particular reference to braking apparatus of the type j g and a'lhigh pressure, Zone.

located along the track for retarding railway cars by frictional engagement of the sides of the car 'wheels'with spring pressed br-lre shoes. 7

Intheoperation of retarders of this'type it has been found desirable to vary the pressure of the brake shoes, and hence the braking effect, to correspond with" the eight of the car to be retarded but if the pressure he too great for a. partic-ularweight of car the car wheels tend to rise up from between the shoes and "ride on top thereof. This matter has been more thoroughly discussed hereinafter and in the co-pending applicationSer. No.

70,599, filed November 21, 1 925, to whichattention is directed. V p I In practice, there is sometimes a variation in the thickness of: the car wheels, and since the pressure exerted by the brake shoes in this typeof brahede'pends on the relative position of the brake shoes and their actuating means, it is obvious that thicker Wheels will receive a greater brakingeflortthan do thinner Wheels, for a given setting of, the braking apparatus, and thus disturb the proper proportioning of thebral'reshoe pressure relative to theniight of the car to be retarded.

With the above and other COlISlClGI'iLtlODS in V 1nind, itis proposed, inaccordance with this invention, to provide means whereby the effect of variationin the thickness of the car wheels will be minimized, in order topermit a relatively close adjustment of the brake shoe pressure to the weight of the car in question, regardless of such variations in car vvheel thickness as occur in practice, More specifi- Cally stated it is proposed to press the brake shoes againstgthe car Wheels by compound spring means arranged so that different springs are initiated with action at different settings of theretarder, and in'thespecific em.- bodiment describedbelow, two such springs are used whereby to give a brake shoe pres sure curve,jplotted as a function of relative movement betwe n, h I a 9. and i s actuator, having two relatively flat straight the brake shoes being carried by brake bars comprises two distinct zones, a 10W pressure,

Further objects, purposes, and characteristic features of this invention will appear as the" description progresses, reference being had to the accoi'npanying drawings, showing solely by way of example, one form of the in vention. In theldrawings Fig. 1 is aplan view of a portion of a car rotarder constructed in accordance with this invention; p i

Fig; 2 is a'sectional elevation on line '22 F t i i i i Fig.3 is a fragmentary sectional-view, to a large scale, of the compound springs and associated parts" used inthe invention; and

'Figs; 4, 5 and, 6 are diagrammatic views showing iressure-inovement curves for the brake shoes. v I

In generahthe construction and arrangement of the parts of the car retarder shown in the drawings are the same as inthe above referred to co -pending application Ser. No. 70,599, and accordingly the following description of such parts, although complete,

will be very brief, and for a more detailed explanationreference may be had to such application.

Referring to Fig. 1, a track formed by rails l,- is equipped witha retarder system con1 prising brake shoes 2 on each side of each rail,

3 formed of articulated sections3 3 etc.

Tl'iejbrake bars or beams 3 are connected, by means to be described in detail below. to lugs i and 5- carried respectively by girder beams or actuating bars at and 5 arrangedside by side in pairs, and operable in opposite directions, at right angles to the track rails 1, means of double angle levers 6, pivoted at; to fixed supports,'-and pivoted at 8 and 9 to the members .4 and u The leversfi are pivotally connected to a. bar 10 arranged to be reolproc-ated, through rod llend lever 12, by means ot er reciprocating pitinan 13, operabletovarious brake setting positions by means of a crank pin 1ft, the said pin being shown as having five operative positions. A

ill

p 71 ,10 and pjfiby suitable electrically operated means, it may be pointed out at this time that the casing in practice preferably includes a suitable electric motor, and suitable circuit controlling means assuming a position depending on the position of the crank pin 14; which circuit cont-roller is connected in a circuit arrangement which includes a plurality oi branch circuits in multiple of which all of these branch circuits are completed within the casing 15 except one branch circuit thereof, and each of these branch circuits is such that it current is permitted to flow therei a in in response to movement of the lever 17 the motor is operated in a direction so as to open the branch circuit in question and close the In other words, the control mechanism for the motor in casing 15 is such that the motor will operate the wheel containing crank pin 14 in a direction corresponding to the direction in which the lever l'Thas been moved and will operate this motor until the crank pin has assumed a position corresponding to that oi the lever 17. These features are somewhat more specifically illustrated and described in the co-pending application above referred to.

The lugs 4 and 5 are each connected to the brake bars 4 and 5, respectively by means which is the same in each case and hence a description of one will'serve for all.

Referring more particularly to Fig. 3, the lug 5 on the actuating bar 5, is connected to the brake bar 3, by a stem 18, having a head 19 thereon which is pivoted to the member 3 by a pin 20. The other end of the stem 18Vis received in an adjustable manner in an internal bore of an externally threaded screw 21, slidably received in the lug 5, and furnished with a bearing plate 22 and lock nuts 23. Slidably arried on the screw 21, is an annular 'washer 24, and a follower 25, the follower being externally threaded and receiving a threaded nut 26 adapted to bear in a socket 27 in the lug 5. Bearing against the inner end of the screw 21, is an annular washer 28 which is slidable on the pin 18 and serves as an abutment for one end of an inner spring 29, the other end of which bears against a face member 30 on the member 19. Surrounding the inner spring 29 is an outer spring 31, hearing at one end against the same face member 30, and at the other end against the member 24. The member 24has a projected rim 24 arranged in line with the annu lar washer 28.

The springs 29 and 31 are initially tensioned between their abutment members so as to contain a trapped tension, whereby, as soon as they are brought into play, they immediately exert a very considerable force, the amount depending upon the amoimt of initial tension in the springs.

. The arrangement of parts described, permits independent adjustment of the initial tension of the springs 29 and 31, and of the distance between the brake shoe and the lug 5. For adjusting the initial tension of the outer springs 31, the washer 24 and the follower 25 are adjusted inwardly or outwardly as the case maybe, while for adjusting the initial tension of the inner spring the screw 21, together with the washer28, is threaded inwardly or outwardly according to the result desired, For adjusting the position of the brake shoe relative to the lug 5, the lock nuts 23 can be adjusted along the screw 21, and in combination with the bearing plate 2 accomplish the desired result. branch circuit which was previously open.

It should be readily understood from the above described structure, that operation of the crank pin 14 operating through the pitman 13 the lever 12 and rod 11 and the bar 10, will rock the lever 6 and'thereby move the lugs 4 in one direction at right angles to the rails 1, while at the same time moving the lugs 5 in the opposite direction. Referring again more particularly to Fig. 3 it will be seen that movement of a lug, such for example as 5", will slide the members 26. 25 and 24 to the left against the tension of outer spring 31, and thereby exert this spring tension against the brake shoe in question, the pressure being dependent, at the initial point, on the trapped tension in the spring, and beyond that point, on the amountof movement between the lug and the brake shoe.

After a given amount of movement of the washer 24, in the case illustrated a movement equal to the distance between the rim 24 and the annular washer 28, the inner spring 29 is brought into initial action and from thispoint on, further relative movement between the lug 5: and the brake shoe, will operate to compress both of the springs and build up the pressure exerted by the brake shoes against the car wheels in accordance with the extent of movement of the lug 5 beyond this point.

The variationin brake shoe pressure cor responding to relative movement between brake shoe and actuating member, has been shown in the curve in Fig. 4, from which it will be seen that the first, and relatively flat part 32 of the curve corresponds to the pressure exerted by-the outer spring 31 only, the upper and relatively steep part 33, 01": the curve corresponds to the pressures exerted by the two springs 29' and 31 in combination, and the vertical portions and 3% represent the initial tensions of the inner and outer springs 29 and 31 respectively.

' On the curve of Fig. 4, a plurality otoporative positionstor the crank pin H ofFig.

l have been indicated by characters 79, 10

' of greater thickness be operated on, the prescrate in a portion otthe curve beyond the point p whereas if the wheel were thinner .111Ot1f'Sl1lfl1f'tfll8 working position o-n -the curve :other tthe uniform portions of thecurve oc-;

- from onezone to the other. :Thus the variathickness of: the car wheels "will-.merely ft the working point along one or the curring the two zones, andhence will not operateto suddenly andjvery greatly vary the actual pressure exerted, from the idealpres sure corresponding to the weight o't theear to be retarded; At the sam'etrnie, by having two separate "zones inthe curve, connected by {a verticalportion, it isgpossibleto buil' eup' a very high braking pressure, by working in sure would rise and the retarder would opthe high pressurezone, without any necessity than normal, it would operate at a point in front of the point 71?. Inpractiee however, the variation trom normal width is generally towards an increased thickness, and since, by

having the vertical part 35 of the curve occur just in front of one operative position,

namely W, a wheel which is thicker than nor :nial, operated on when the retarder is set at position 2), will shift the working point beyond the point p and hence will not vary the pressure from the desired one, to as great an extent, as it the part 35 of the curve were just beyond 79 Should. it be found however, that the variation from the normal wheel thickness, is to wards a thinner wheel, then the pressure curve would be arranged so that the vertical portion 35 thereof would occur just beyond an operative position such for instance as 79 so that, as in the case before considered, the variation in the wheel thickness would not change the working point of the car retardcr from one zone to the other. This has been illustrated graphically in Fig. 5 of the drawings. 7

If the wheel thickness varies on either side of normal, then the vertical part 35 of the curve would be placed midway between two settings, such as p and p of the retarder, as graphically shown in Fig. 6. The con. struction described gives a retarder operating along a pressure curve having two zones, a rather flat, and a comparativelysteep zone, and thus, for light cars, its operation is in of view.

course, is desirable' from aj mechanical point Coils rin 's inhcrentl have substantiallv a straight line characteristic, that is, the pres sure with which a spring is compressed varies directly with the: extent of deformation. By reason-of the fact that the trouble of cars ridingout at the top between brake shoes is experienced principallyjfor l'ightcarsit is found expedient to 1 have 'thepressuredeformation characteristicmuch steeper for the heavy ears and higher pressures than for "the light cars and- 1 'wer pressures. Since tis nnposs'ible'to design asmgle "and simple spring having a; pressure-deformation characteristic such as justleXpla-ined, applicant has designed acompound spring arrange ment which has a 'pressure-deformation which approaches the characteristic j ust mentioned.- In other word's,'the carr'etarder embodyin the present invention includes spring mechanism which has an upturned pressuredeforinatlon charactcristlc as compared w th a straight line pressure-deformation characteristic as is true of a simple coilspring,

The init al tension of the two springs 29 and-31, can of course be adjusted in accordthe flat zone where variation in wheel thickbe seen that a retarder has been produced, in

which the pressures of the brake shoes vary according to a curve having an upper and steep zone, and a lower and flat zone, connected'by a vertical portion, the curve being arranged relative to the operative positions of the retarder so that the usual variation in thickness of car wheels from the normal will ance'with the operating conditionsto be met,

as can 'alsothe strength of thesprings em ployed, Merely by, wayof example, it'is noted that inone case it 'w'asfound best to employ an outer spring having initial compression, and a strength of 1,000 pounds per 5 compression, with an inner spring having initial compression and a strength of 1000 pounds per compression.

The above rather specific description of one form of the present invention is given solely by way of illustration, and is not intended, in any manner whatsoever, in a limiting sense. Obviously, the invention can assume many different physical forms, and is susceptible of numerous inodifications and all such'forms and modifications are intended to be included in this application, as come within the scope of the appended claims.

Having 'described my invention, I now claim :1. In a car retarder of the type engaging the; wheels of a passing car, a brake shoe, a shoe actuator, means slidably inter-connecting the shoe and actuator, a plurality of initially tensioned springs carried on said means between the shoe and actuator, the springs being arranged to initiate a relative moving effort on theshoe and actuator at difierent relative" positions of said shoe and actuator.

2. In a car retarder of the type engaging the Wheels of passing cars, a brake shoe arranged to engage the wheel of a passing car,

a shoe actuator, and multiple spring positioned between the shoe; and its actuator of which each spring has trapped pressure and of which one spring is not further compressed until the other spring has been deformed to a predetermined extent.

3. In a car retarder of the type engaging the sides of the wheels of passing cars, a

brake shoe arranged to engage the wheel of a passing car, a shoe actuator, and multiple initially tensioned springs positioned between the shoe and its actuator of which one 7 spring is not further compressed until another spring has been deformed to a predetermined extent.

4. In a car retarder of the' type engaging the sides of thewheels of passing cars, a

brake shoe arranged to engage the wheel of a passing car, a shoe actuator, multiple initiinitially tensioned springs arranged in inultiplecarried by said means between the shoe and actuator and arranged to be brought into action at difi'erent positions of the actuator with respect to the shoes. In testimony whereof I afliX my signature.

NED C. L. BROWN. 

